| Summary: | Meio-and macrofauna density and biomass were estimated at the OMEX-transect across the continental slope of the Goban Spur at water depths ranging from 208 to 4460 m in the north-east Atlantic. A linear increase in the ratio between meio-and macrofauna densities with increasing water depth was found. At the continental shelf meiofauna densities were *50 times higher than macrofauna densities, whereas in the abyss meiofauna densities were more than 1000 times higher. This change in ratio was due to a signi¢cant decrease in macrofauna densities with increasing water depth, whereas the meiofauna densities stayed more or less at the same level. The ratio in biomass between meio-and macrofauna showed a dip at *1000 m. At this depth macrofauna biomass was *55 times higher than meiofauna biomass, whereas at *4500 m macrofauna biomass was only about three times higher. Macrofauna biomass was high at *1000 m, due to the high mean individual weight of the macrofauna, whereas meiofauna biomass and mean individual weight were low at this depth. Meiofauna consisted of *90% nematodes. Within the macrofaunal fraction (40.5 mm) a linear increase in the ratio between nematodes and macrofauna sensu stricto with depth was found. At the deepest station *20% of the macrofaunal fraction were nematodes, at the shallowest station only *2%. Thus, large nematodes became relatively more important with increasing water depth. Within the macrofauna a decrease in the abundance of ¢lter-and surface deposit-feeders relative to the subsurface depositfeeders with increasing water depth was observed, which may be related to a change in food input. As no decrease in mean individual weight with increasing water depth within either group could be observed, the change in meio:macrofauna ratios along the OMEX-transect merely re£ects a change in taxonomic (functional) composition, rather than a change in size.
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